Method for producing a stretchresistant coated abrasive product



3,487,593 METHOD FOR PRODUCING A STRETCH- RESISTANT COATED ABRASIVEPRODUCT Daniel R. Vinard, Le Vesinet, France, assignor to NortonCompany, Worcester, Mass., a corporation of Massachusetts No Drawing.Filed Aug. 29, 1967, Ser. No. 663,985 Claims priority,applicagion6France, Oct. 31, 1966,

8 ,30 Int. Cl. B24d 11/02 U.S. Cl. 51-293 1 Claim ABSTRACT OF THEDISCLOSURE The use of a tightly woven cloth backing containing polynosicthreads as the warp or fill threads of the cloth in an amount suflicientto reduce the stretch of the finished coated abrasive article by atleast 25% in the direction in which the polynosic threads extend.

The present present invention has general reference to coated abrasiveproducts and more particularly relates to the backings suitable for themanufacture of coated abrasive products.

It is known in certain industries to use so-called polynosic threadswhich consist of filaments made of regenerated cellulose, the chains ofwhich have an orientated structure and a high molecular weight, andwhich may be obtained by the viscose process, the latter being suitablymodified.

It is known that polynosic threads have a very orientated structure, ahigh breaking strength and a high modulus of elasiticity. Owingparticularly to their breaking strength, they have been utilizedaccording to the former technique, as a reinforcement or armature forapplications including a coating constituted by rubber or equivalentmaterial, the threads being imbedded in the product. Conveyor belts andtires, for example, have been manufactured with such polynosic threads.

The researches which have lead to the invention have revealed that it ispossible to make use in new fashion of the characteristics of polynosicthreads corresponding to a high modulus of elasticity for manufacturingbackings for coated abrasive products, every time it is desired toobtain for the manufactured product a specific elongation of smallvalue. As a matter of fact, it is known that the coated abrasiveproducts, particularly those which are utilized in belt form must becapable of lending themselves to an elongation of small value in onedirection which corresponds to the direction in which the stresses areexerted during the abrasion work.

Moreover, researches have shown that the polynosic threads have a goodproperty of absorbing aqueous suspensions, a characteristic whichremained unemployed in the case of a coating made with a rubber mass.

The invention makes use of these characteristics, and is materialized ina backing for coated abrasive products constituted by a woven backing inwhich the weft threads or the warp threads of the cloth are constitutedat least partly by polynosic threads.

The warp or the weft of said cloth (as the case may be) may beconstituted by usual cotton, which is the material generally utilizedfor the manufacture of the known woven backings.

According to a feature of the invention, the texture of the wovenbacking including polynosic threads as warp threads or weft threadsshould be as tight as possible for staving off sliding or distortion ofthe cloth, and the weave is suitably constituted by a cotton serge i dStates Patent 3,487,593 Patented Jan. 6, 1970 ice or satin weave so asto increase the resistance to distortion and the compactness of thecloth. The weight of the threads in the chosen direction is at leastequal to 60 g./sq. meter and the total weight of the cloth is preferablyequal to or higher than 200 g./ sq. meter. This characteristic is inopposition to that presented by the textures of knownreinforcementsconstituted by polynosic threads (or containing such threads) which, asa rule are very loose so as to permit the cloth to become distorted andelongated. As a matter of fact, in the known textures, the polynosicthreads are provided only to enhance the mechanical resistance of thereinforcement owing to their breaking strength. In the case of the newapplication which is the object of the invention, the characteristic ofsmall elongation presented by the polynosic threads is utilized in thedesired direction while taking into consideration the work which isenvisaged for the product.

Of course, these polynosic threads may, as aforesaid, constitute thewhole weft or only a part thereof, or alternatively the whole warp oronly a part thereof, according to the desiredcharacteristics. However,it could be possible, without departing from the scope of the invention,to manufacture a backing for coated abrasive products, in which both theweft and the warp would be constituted wholly or partly by polynosicthreads, although normally this dual utilization does not meet theconditions of resistance to elongation in one single direction which areto be obtained for a satisfactory backing for coated abrasive productsutilized in band form.

The utilization of polynosic threads for the manufacture of wovenbackings for coated abrasive products advantageously facilitates thecoating operation according to the finishing methods which are generallyutilized for the backings made of woven cotton, according to whichanimal glues, starch paste, etc., are utilized. The researches whichhave led to the invention have shown, as previously indicated, thatthese polynosic threads have a good property of absorption for aqueoussuspensions. This characteristic is necessary for realizing coatedabrasive products,in order to ensure retention of the abrasive grains.

The invention also includes, as new articles of manufacture, the coatedabrasive products, particularly in the form of belts, comprising a wovenbacking, the warp or the weft of which is constituted at least partly bypolynosic threads.

The way of manufacturing a woven backing according to the invention anda coated abrasive product comprising such a backing including polynosicthreads are indicated hereafter by way of non-limitative example.

EXAMPLE The unbleached material utilized for constituting the backingaccording to the invention is a A satin including a cotton warp made of38 threads Nm. 28 and a weft made of polynosic threads including 21threads Nm. 10, 7. Such a backing may be woven in conventional fashion.

The backing being thus constituted, the coating utilized for themanufacture of the abrasive product is performed according to thefinishing methods generally utilized for the cloths made of cotton.After finishing is effected, the maximum elongation at rupture of thefinished cloth in the direction of the weft is reduced by about 25% withrespect to that obtained with a cloth made of natural cotton.

The coating of the abrasive grains may then be performed by means ofusual phenolic binders. It has been stated that the maximum elongationat rupture of the coated abrasive product, which is thus obtained, whilemeasured in the direction of the weft, is reduced by nearly 50% withrespect to that which is obtained with a usual cloth made of naturalcotton.

The results which are obtained, as far as the reduction of elongation atrupture is concerned, are clearly shown by comparative tests made withan unbleached material, as aforesaid, utilized according to theinvention and with an unbleached material made of 100% cotton, Whilemeasuring the elongation at rupture in the direction of the weft. Theweight of each unbleached material is about 350 g./ sq. meter. Theseresults are indicated in the following table:

Weft made of polynosic 100% threads cotton Finished cloth, percent 1722. 5 Coated product, percent 14. 5 26 (Silicon carbide, grain No. 50and phenolic binders) be varied in the field of technical equivalencieswithout departing from the scope of the invention.

I claim:

1. In a method for producing a coated abrasive product having reducedstretch in at least one direction, wherein said coated abrasive productconsists of abrasive grains adhesively bonded to a flexible backing, theimprovement which comprises:

(a) providing a woven backing for said coated abrasive productcontaining a plurality of polynosic threads having a weight of at leastg./m. extending in at least one direction; and

(b) weaving said threads in a satin weave pattern into said wovenbacking in a tight, closely-packed relationship to minimize sliding anddistortion of said backing.

References Cited UNITED STATES PATENTS 2,284,738 6/1942 Hurst 5l3032,397,808 4/1946 Riding 51303 2,817,371 12/1957 Bussiere 51298.13,419,652 12/1968 Kubota et al 264189 DONALD J. ARNOLD, Primary ExaminerUS. Cl. X.R. 51298, 303

